The present invention relates to foam stabilizers and more particularly to a new amine oxide foam stabilizer especially efficient for stabilizing foams containing alkyl benzene sulfonate foaming agents.
Until the early 1930's, cleaning products, such as those used for cleaning clothes, washing dishes, shampooing hair and bathing, were invariably based upon fatty acid soaps (e.g. alkali metal or amine salts of fatty acids). These soaps had the ability to provide excellent cleaning and high foaming or lathering properties when used in distilled or soft water; however, in hard water containing significant concentrations of calcium and/or magnesium ions (e.g. 50-300 ppm), insoluble soaps would form which prevented the cleaning action from taking place and prevented foaming until all of the calcium and/or magnesium ions had precipitated out of the water. Besides leaving unacceptable deposits on clothing or hair, for example, the insoluble soaps resulted in a great waste of the fatty acid soap detergents. In the early 1930's, fatty alcohol sulfates, particularly sodium lauryl sulfate, were developed for this market. These anionic surface active agents give high flask foams and unlike the the fatty acid soaps which they replaced such anionic surface active agents are not affected by hard water in that no insoluble precipitates develop and their initial foaming properties are unaffected in hard water.
Fatty alcohol sulfates, however, have two major problems. The first is that the excellent initial foam is not stable and tends to collapse quickly during use. The second is that the fatty alcohol sulfates are expensive. The first problem can be overcome by employing a foam stabilizer in the formulations for extending the foam life. The second problem necessitated development of alternative anionic surfactants. An example of a much lower cost anionic surface active agent having high initial foam in hard water is an alkyl benzene sulfonate (for example, sodium dodecyl benzene sulfonate). Another lower cost anionic surface active agent which gives high flash foams in hard water is an alpha olefin sulfonate (for example, sodium dodecyl sulfonate). Both of these latter, lower cost anionic surface active agents require a foam stabilizer for extending the life of the foam in use.
Heretofore, foam stabilizers generally were alkanolamides and amine oxides. Both the alkanolamides and the amine oxides typically are synthesized from long-chain fatty molecules which are derived from, for example, lauric-containing triglyceride oils such as coconut oil or palm kernel oil. Typical present day, commercially used alkanolamide foam stabilizers include, for example, lauric or coco monoethanolamide, lauric or coco diethanol amide, and lauric or coco isopropanolamide; and amine oxides include, for example, lauryl or coco dimethylamine oxide, lauryl or coco bis(2-hydroxyethyl)amine oxide, lauryl or coco beta-hydroxydimethyl amine oxide, and lauryl or coco beta-hydroxy bis (2-hydroxyethyl) amine oxide. Further amine oxide foam stabilizers can be found in U.S. Pat. Nos. 3,449,430, 3,449,431, and 3,456,012.
The amine oxides function well as foam stabilizers for fatty alcohol sulfates, fatty ether alcohol sulfates, reasonably well for alpha olefin sulfonates, but not for alkyl benzene sulfonates. The alkanolamides function well for all of the above-listed anionic surfactants; however, the alkanolamides tend to be irritating to the skin and eye, and many are difficult to handle and store practically.